Steering shaft

Abstract

A steering shaft includes a sleeve member; a shaft member inserted into the sleeve member; at least two rolling element sets each including a plurality of rolling elements, and each being disposed between the sleeve member and the shaft member, the rolling element sets being arranged in a circumferential direction; a plate-shaped gap regulating member disposed between one of the rolling element sets and one of the shaft member and the sleeve member, arranged to be moved in an axial direction, and arranged to form a gap between the shaft member and the sleeve member when the gap regulating member is moved axially in a first direction, and to close the gap when the gap regulating member is moved axially in a second direction opposed to the first direction; and an urging member arranged to urge the gap regulating member in the second direction.

1 . A steering shaft comprising: 
 a sleeve member;    a shaft member inserted into the sleeve member;    at least two rolling element sets each including a plurality of rolling elements, and each being disposed between the sleeve member and the shaft member, the rolling element sets being arranged in a circumferential direction;    a plate-shaped gap regulating member disposed between one of the rolling element sets and one of the shaft member and the sleeve member, arranged to be moved in an axial direction, and arranged to form a gap between the shaft member and the sleeve member when the gap regulating member is moved axially in a first direction, and to close the gap when the gap regulating member is moved axially in a second direction opposed to the first direction; and    an urging member arranged to urge the gap regulating member in the second direction.    
   
   
       2 . The steering shaft as claimed in  claim 1 , wherein the sleeve member includes a rolling surface on which the rolling elements are rolled; the shaft member includes a rolling surface which confronts the rolling surface of the sleeve member, and which is substantially parallel to the rolling surface of the sleeve member; and the other of the rolling element sets is disposed between the rolling surface of the sleeve member and the rolling surface of the shaft member.  
   
   
       3 . The steering shaft as claimed in  claim 2 , wherein the gap regulating member extends from a first end to a second end in the first direction, the gap regulating member includes a taper surface sloping toward the first end of the gap regulating member so that a thickness of the gap regulating member becomes smaller gradually toward the first end; and the other of the shaft member and the sleeve member includes a taper surface confronting the taper surface of the gap regulating member, and extending substantially in parallel to the taper surface of the gap regulating member.  
   
   
       4 . The steering shaft as claimed in  claim 2 , wherein the gap regulating member includes a plurality of projection sets arranged in a longitudinal direction of the gap regulating member; each of the projection sets of gap regulating member includes a plurality of projections arranged in a widthwise direction of the gap regulating member which is perpendicular to the longitudinal direction of the gap regulating member; and each of the projections of the projecting sets projects toward the other of the shaft member and the sleeve member.  
   
   
       5 . The steering shaft as claimed in  claim 4 , wherein each of the projections of the gap regulating member is a spherical projection.  
   
   
       6 . The steering shaft as claimed in  claim 5 , wherein the other of the shaft member and the sleeve member includes a plurality of recessed portions each having a taper surface confronting one of the projections of the gap regulating member; and each of the recessed portions slopes so that a depth of the each of recessed portions becomes smaller gradually in the second direction.  
   
   
       7 . The steering shaft as claimed in  claim 2 , wherein the gap regulating member includes a plurality of projections projecting toward the other of the shaft member and the sleeve member; and the projections of the gap regulating member is arranged in a longitudinal direction of the gap regulating member.  
   
   
       8 . The steering shaft as claimed in  claim 7 , wherein the gap regulating member extends from a first end to a second end in the first direction; and each of the projections of the gap regulating member has a taper surface sloping toward the first end of the gap regulating member so that a thickness of the projection becomes smaller gradually toward the first end.  
   
   
       9 . The steering shaft as claimed in  claim 8 , wherein the other of the shaft member and the sleeve member includes a plurality of recessed portions each having a taper surface confronting one of the projections of the gap regulating member, and extending substantially in parallel to the one of the taper surfaces of the projections of the gap regulating member.  
   
   
       10 . The steering shaft as claimed in  claim 1 , wherein the steering shaft comprises three rolling element sets including the at least two rolling element sets; the shaft member has a hexagonal cross section; the sleeve member has a hexagonal hollow cross section; and the rolling element sets are arranged alternately in the circumferential direction between side surfaces of the shaft member and side surfaces of the sleeve member.  
   
   
       11 . The steering shaft as claimed in  claim 1 , wherein three rolling element sets including the at least two rolling element sets; the shaft member has a triangle cross section; the sleeve member has a triangle hollow cross section; and each of the rolling element sets are arranged in the circumferential direction between one of side surfaces of the shaft member and one of side surfaces of the sleeve member.  
   
   
       12 . The steering shaft as claimed in  claim 1 , wherein each of the rolling elements is a roller; the steering shaft further comprises a roller holder holding the rollers arranged in the axial direction.  
   
   
       13 . The steering shaft as claimed in  claim 1 , wherein the gap regulating member includes an axial portion extending from a first end to a second end in the first direction, and being disposed between the shaft member and the sleeve member, and a head portion extending from the second end of the axial portion in a direction substantially perpendicular to the axial portion.  
   
   
       14 . The steering shaft as claimed in  claim 1 , wherein the steering shaft further comprises a fastening device inserted into the shaft member, and arranged to support the urging member to urge the gap regulating member in the second direction.  
   
   
       15 . The steering shaft as claimed in  claim 3 , wherein the other of the shaft member and the sleeve member is formed with a groove extending in the axial direction; and the taper surface of the gap regulating member is formed with a raised-portion extending in the axial direction so that the gap regulating member is moved axially along the groove of the other of the shaft member and the sleeve member.